Drill string components resistant to jamming

ABSTRACT

Aspects of the present invention include drill string components having a thread extending around a body. The leading end of the thread can have a configuration that resists jamming and cross-threading. In particular, the leading end of the thread can include a planar surface normal to the body. The leading end of the thread can provide an abrupt transition to full thread depth that helps reduce or eliminate cross-threading. The leading end of the thread can be oriented at an angle relative to the axis of the drill string component. When mating male and female threads are similarly structured, the mating threads slide together along an interface at the thread start face and are drawn into a fully thread-coupled condition. The thread starts may have full circumference mating with no jamming positions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.13/354,189, filed Jan. 19, 2012, “DRILL STRING COMPONENTS RESISTANT TOJAMMING,” and claims the benefit of U.S. Provisional Application No.61/436,331, filed Jan. 26, 2011, entitled “THREAD START FOR THREADEDCONNECTORS,” the contents of which are hereby incorporated by referencein their entirety.

BACKGROUND OF THE INVENTION

1. The Field of the Invention

Aspects of the present invention relate generally to components andsystem for drilling. In particular, aspects of the present inventionrelate to drill components that resist jamming during make-up.

2. The Relevant Technology

Threaded connections have been well known for ages, and threads providea significant advantage in that a helical structure of the thread canconvert a rotational movement and force into a linear movement andforce. Threads exist on many types of elements, and can be used inlimitless applications and industries. For instance, threads areessential to screws, bolts, and other types of mechanical fasteners thatmay engage a surface (e.g., in the case of a screw) or be used inconnection with a nut (e.g., in the case of a bolt) to hold multipleelements together, apply a force to an element, or for any othersuitable purpose. Threading is also common in virtually any industry inwhich elements are mechanically fastened together. For instance, inplumbing applications, pipes are used to deliver liquids or gasses underpressure. Pipes may have threaded ends that mate with correspondingthreads of an adjoining pipe, plug, adaptor, connector, or otherstructure. The threads can be used in creating a fluid-tight seal toguard against fluid leakage at the connection site.

Oilfield, exploration, and other drilling technologies also makeextensive use of threading. For instance, when a well is dug, casingelements may be placed inside the well. The casings generally have afixed length and multiple casings are secured to each other in order toproduce a casing of the desired height. The casings can be connectedtogether using threading on opposing ends thereof. Similarly, asdrilling elements are used to create a well or to place objects inside awell, a drill rod or other similar device may be used. Where the depthof the well is sufficiently large, multiple drill rods may be connectedtogether, which can be facilitated using mating threads on opposing endsof the drill rod. Often, the drill rods and casings are very large andmachinery applies large forces in order to thread the rods or casingstogether.

Significant efforts have been made to standardize threading, andmultiple threading standards have been developed to allow differentmanufacturers to produce interchangeable parts. For instance exemplarystandardization schemes include Unified Thread Standard (UTS), BritishStandard Whitworth (BSW), British Standard Pipe Taper (BSPT), NationalPipe Thread Tapered Thread (NPT), International Organization forStandardization (ISO) metric screw threads, American Petroleum Institute(API) threads, and numerous other thread standardization schemes.

While standardization has allowed greater predictability andinterchangeability when components of different manufactures are matchedtogether, standardization has also diminished the amount of innovationin thread design. Instead, threads may be created using existingcross-sectional shapes—or thread form—and different combinations ofthread lead, pitch, and number of starts. In particular, lead refers tothe linear distance along an axis that is covered in a completerotation. Pitch refers to the distance from the crest of one thread tothe next, and start refers to the number of starts, or ridges, wrappedaround the cylinder of the threaded fastener. A single-start connectoris the most common, and includes a single ridge wrapped around thefastener body. A double-start connector includes two ridges wrappedaround the fastener body. Threads-per-inch is also a threadspecification element, but is directly related to the thread lead,pitch, and start.

While existing threads and thread forms are suitable for a number ofapplications, continued improvement is needed in other areas. Forinstance, in high torque, high power, and/or high speed applications,existing thread designs are inherently prone to jamming. Jamming is theabnormal interaction between the start of a thread and a mating thread,such that in the course of a single turn, one thread partially passesunder another, thereby becoming wedged therewith. Jamming can beparticularly common where threaded connectors are tapered.

In tapered threads, the opposing ends of male and female components maybe different sizes. For instance, a male threaded component may taperand gradually increase in size as distance from the end increases. Toaccommodate for the increase in size, the female thread may be larger atthe end. The difference in size of tapered threads also makes taperedthreads particularly prone to jamming, which is also referred to ascross-threading. Cross-threading in tapered or other threads can resultin significant damage to the threads and/or the components that includethe threads. Damage to the threads may require replacement of thethreaded component, result in a weakened connection, reduce thefluid-tight characteristics of a seal between components, or have othereffects, or any combination of the foregoing.

For example, tail-type thread starts have crests with a joint taper. Ifthe male and female components are moved together without rotation, thetail crests can wedge together. If rotated, the tail crests can alsowedge when fed based on relative alignment of the tails. In particular,as a thread tail is typically about one-half the circumference inlength, and since the thread has a joint taper, there is less than halfof the circumference of the respective male and female componentsproviding rotational positioning for threading without wedging. Suchpositional requirements may be particularly difficult to obtain inapplications where large feed and rotational forces are used to matecorresponding components. For instance, in the automated making ofcoring rod connections in the drilling industry, the equipment mayoperate with sufficient forces such that jamming, wedging, orcross-threading is an all too common occurrence.

Furthermore, when joining male and female components that are in anoff-center alignment, tail-type connections may also be prone tocross-threading, jamming, and wedging. Accordingly, when the male andfemale components are fed without rotation, the tail can wedge into amating thread. Under rotation, the tail may also wedge into a matingthread. Wedging may be reduced, but after a threading opportunity (e.g.,mating the tip of the tail in opening adjacent a mating tail), wedgingmay still occur due to the missed threading opportunity andmisalignment. Off-center threads may be configured such that a mid-tailcrest on the mail component has equal or corresponding geometry relativeto the female thread crest.

As discussed above, threaded connectors having tail-type thread startscan be particularly prone to thread jamming, cross-threading, wedging,joint seizure, and the like. Such difficulties may be particularlyprevalent in certain industries, such as in connection with the designsof coring drill rods. The thread start provides a leading end, or firstend, of a male or female thread and mates with that of a mating threadto make a rod or other connection. If the tail-type thread starts jam,wedge, cross-thread, and the like, the rods may need to be removed froma drill site, and can require correction that requires a stop indrilling production.

Additionally, drill rods commonly make use of tapered threads, which arealso prone to cross-threading difficulties. Since a coring rod may havea tapered thread, the tail at the start of the male thread may besmaller in diameter than that of the start of the female thread. As aresult, there may be transitional geometry at the start of each threadto transition from a flush to a full thread profile. Because the threadstart and transitional geometry may have sizes differing from that ofthe female thread, the transitional geometry and thread start may mateabnormally and wedge into each other.

If there is a sufficient taper on the tail, the start of the male threadmay have some clearance to the start of the female thread, such as wherethe mid-tail geometry corresponds to the geometry of the female thread.However, the transitional geometry of the start of the thread maynonetheless interact abnormally with turns of the thread beyond thethread start, typically at subsequent turns of mating thread crests,thereby also resulting in jamming, cross-threading, wedging, and thelike. Thus, the presence of a tail generally acts as a wedge with amating tail, thereby increasing the opportunity and probability ofthread jamming.

In certain applications, such as in connection with drill rigs, multipledrill rods, casings, and the like can be made up. As more rods orcasings are added, interference due to wedging or cross-threading canbecome greater. Indeed, with sufficient power (e.g., when made up usinghydraulic power of a drill rig) a rod joint can be destroyed. Coringrods in drilling applications also often have threads that are coarsewith wide, flat threaded crests parallel to mating crests due to amating interference fit or slight clearance fit dictated by many drillrod joint designs. The combination of thread tails and flat, parallelthread crests on coarse tapered threads creates an even larger potentialfor cross-threading interaction, which may not otherwise be present inother applications.

The limitations of tail-type thread designs are typically brought aboutby limitations of existing machining lathes. In particular, threads aretypically cut by rotational machining lathes which can only graduallyapply changes in thread height or depth with rotation of the part.Accordingly, threads are generally formed to include tails havinggeometry and tails identical or similar to other portions of the threadstart. For instance, among other things, traditional lathes are notcapable of applying an abrupt vertical or near vertical transition froma flush to full thread profile to rotation of the part during machiningThe gradual change is also required to remove sharp, partial featureedges of material created where the slight lead, or helix angle, of thethread meets the material being cut.

Thus, drawback with traditional threads can be exacerbated with drillingcomponents. In particular, the joints of the drill string components canrequire a joint with a high tension load capacity due to the length andweight of many drill strings. Furthermore, the joint will often need towithstand numerous makes and breaks since the same drill stringcomponents may be installed and removed from a drill string multipletimes during drilling of a borehole. Similarly, the drill stringcomponents may be reused multiple times during their life span.Compounding these issues is the fact that many drilling industries, suchas exploration drilling, require the use of thin-walled drill stringcomponents. The thin-wall construction of such drill string componentscan restrict the geometry of the threads.

Accordingly, a need exists for an improved thread design that reducesjamming and cross threading.

SUMMARY

One or more aspects of the present invention overcome one or more of theforegoing or other problems in the art with drilling components, tools,and systems that provide for effective and efficient making of threadedjoints. For example, one or more aspects of the present inventioninclude drill string components resistant to jamming andcross-threading. Such drill string components can reduce or eliminatedamage to threads due to jamming and cross-threading. In particular, oneor more aspects include drill string components having threads with aleading end or thread start oriented at an acute angle relative to thecentral axis of the drill string component. Additionally oralternatively, the leading end of the thread can provide an abrupttransition to full thread depth and/or width.

For example, one aspect of a threaded drill string component thatresists jamming and cross-threading includes a hollow body having afirst end, an opposing second end, and a central axis extending throughthe hollow body. The drill string component also includes a threadpositioned on the first end of the hollow body. The thread comprises aplurality of helical turns extending along the first end of the hollowbody. The thread has a thread depth and a thread width. The threadcomprises a leading end proximate the first end of the hollow body. Theleading end of the thread is orientated at an acute angle relative tothe central axis of the hollow body. In one exemplary aspect, theleading end of the thread faces toward an adjacent turn of the thread.Optionally, in a further aspect, the leading end of the thread facestoward the first end of the hollow body.

Additionally, another aspect of a threaded drill string component thatresists jamming and cross threading includes a body, a box end, anopposing pin end, and a central axis extending through the body. Thedrill string component also includes a female thread positioned on thebox end of the body. The female thread has a depth and a width.Additionally, the drill string component also includes a male threadpositioned on the pin end of the body. The male thread has a depth and awidth. Each of the female thread and the male thread comprises a leadingend. The leading end of each of the female thread and the male threadcomprises a planar surface extending normal to the body. In one aspect,the planar surface of the leading end of the female thread can extendalong the entire width and the entire depth of the female thread.Similarly, in another aspect, the planar surface of the leading end ofthe male thread can extend along the entire width and the entire depthof the male thread.

In addition to the foregoing, an aspect of a method of making a joint ina drill string without jamming or cross threading involves inserting apin end of a first drill string component into a box end of a seconddrill string component. The method also involves rotating the firstdrill sting component relative to the second drill string component;thereby abutting a planar leading end of a male thread on the pin end ofthe first drill string component against a planar leading end of afemale thread on the box end of the second drill string component. Theplanar leading end of the male thread is oriented at an acute anglerelative to a central axis of the first drill string component.Similarly, the planar leading end of the female thread is oriented at anacute angle relative to a central axis of the second drill stringcomponent. Additionally, the method involves sliding the planar leadingend of the male thread against and along the planar leading end of thefemale thread to guide the male thread into a gap between turns of thefemale thread.

Additional features and advantages of exemplary aspects of the inventionwill be set forth in the description which follows, and in part will beobvious from the description, or may be learned by the practice of suchexemplary aspects. The features and advantages of such aspects may berealized and obtained by means of the instruments and combinationsparticularly pointed out in the appended claims. These and otherfeatures will become more fully apparent from the following descriptionand appended claims, or may be learned by the practice of such exemplaryaspects as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which the above-recited and otheradvantages and features of the invention can be obtained, a moreparticular description of the invention briefly described above will berendered by reference to specific embodiments thereof which areillustrated in the appended drawings. It should be noted that thefigures are not drawn to scale, and that elements of similar structureor function are generally represented by like reference numerals forillustrative purposes throughout the figures. Understanding that thesedrawings depict only typical embodiments of the invention and are nottherefore to be considered to be limiting of its scope, the inventionwill be described and explained with additional specificity and detailthrough the use of the accompanying drawings in which:

FIG. 1 illustrates a side view of a male end of a drill string componentand a cross-sectional view of a female end of another drill stringcomponent each having a thread with a leading end in accordance with oneor more aspects of the present invention;

FIG. 2 illustrates a side view of a male end of a drill string componentand a cross-sectional view of a female end of another drill stringcomponent each having a thread with a leading end in accordance with oneor more aspects of the present invention;

FIG. 3 illustrates a side view of an exploded drill string having drillstring components having leading ends in accordance with one or moreaspects of the present invention; and

FIG. 4 illustrates a schematic diagram of a drilling system includingdrill string components having leading ends in accordance with one ormore aspects of the present invention.

DETAILED DESCRIPTION

The present invention can be understood more readily by reference to thefollowing detailed description, examples, drawing, and claims, and theirprevious and following description. However, before the present devices,systems, and/or methods are disclosed and described, it is to beunderstood that this invention is not limited to the specific devices,systems, and/or methods disclosed unless otherwise specified, as suchcan, of course, vary. It is also to be understood that the terminologyused herein is for the purpose of describing particular aspects only andis not intended to be limiting.

The following description of the invention is provided as an enablingteaching of the invention in its best, currently known embodiment. Tothis end, those skilled in the relevant art will recognize andappreciate that many changes can be made to the various aspects of theinvention described herein, while still obtaining the beneficial resultsof the present invention. It will also be apparent that some of thedesired benefits of the present invention can be obtained by selectingsome of the features of the present invention without utilizing otherfeatures. Accordingly, those who work in the art will recognize thatmany modifications and adaptations to the present invention are possibleand can even be desirable in certain circumstances and are a part of thepresent invention. Thus, the following description is provided asillustrative of the principles of the present invention and not inlimitation thereof.

Aspects of the present invention are directed toward drillingcomponents, tools, and systems that provide for effective and efficientmaking of threaded joints. For example, one or more aspects of thepresent invention include drill string components resistant to jammingand cross-threading. Such drill string components can reduce oreliminate damage to threads due to jamming and cross-threading. Inparticular, one or more aspects include drill string components havingthreads with a leading end or thread start oriented at an acute anglerelative to the central axis of the drill string component. Additionallyor alternatively, the leading end of the thread can provide an abrupttransition to full thread depth and/or width.

Reference will now be made to the drawings to describe various aspectsof one or more aspects of the invention. It is to be understood that thedrawings are diagrammatic and schematic representations of one or moreaspects, and are not limiting of the present disclosure. Moreover, whilevarious drawings are provided at a scale that is considered functionalfor one or more aspects, the drawings are not necessarily drawn to scalefor all contemplated aspects. The drawings thus represent an exemplaryscale, but no inference should be drawn from the drawings as to anyrequired scale.

As used throughout, the singular forms “a,” “an” and “the” includeplural referents unless the context clearly dictates otherwise. Thus,for example, reference to “turn” can include two or more such turnsunless the context indicates otherwise.

Ranges can be expressed herein as from “about” one particular value,and/or to “about” another particular value. When such a range isexpressed, another aspect includes from the one particular value and/orto the other particular value. Similarly, when values are expressed asapproximations, by use of the antecedent “about,” it will be understoodthat the particular value forms another aspect. It will be furtherunderstood that the endpoints of each of the ranges are significant bothin relation to the other endpoint, and independently of the otherendpoint.

As used herein, the terms “optional” or “optionally” mean that thesubsequently described event or circumstance may or may not occur, andthat the description includes instances where said event or circumstanceoccurs and instances where it does not.

In the following description, numerous specific details are set forth inorder to provide a thorough understanding of the present invention. Itwill be obvious, however, to one skilled in the art that the presentdisclosure may be practiced without these specific details. In otherinstances, well-known aspects of thread specifications, threadmanufacturing, in-field equipment for connecting threaded components,and the like have not been described in particular detail in order toavoid unnecessarily obscuring aspects of the disclosed aspects.

Turning now to FIGS. 1 and 2, optional aspects of threaded drill stringcomponents are illustrated. The threaded drill string components can bejoined while avoiding or reducing the risk of cross-threading or jammingare described in particular detail below. As shown by FIG. 1, a firstdrill string component 102 can comprise a body 103 and a male connectoror pin end 104. A second drill string component 106 can include a body107 and a female connector or box end 108. The pin end 104 of the firstdrill string component 106 can be configured to connect to the box end108 of the second drill string component 106.

In one or more aspects, each drill string component 102, 106 cancomprise a hollow body having a central axis 126 extending there throughas shown in FIGS. 1 and 2. In alternative aspects, one or more of thedrill string components 102, 106 can comprise a solid body (such as apercussive drill rod or drill bit) or a partially hollow body.

The pin end 104 can include a male thread 110 (i.e., a thread thatprojects radially outward from outer surface of the pin end 104). Thebox end 108, on the other hand, can include a female thread 112 (i.e., athread that projects radially inward from an inner surface of the boxend 108). The male thread 110 and the female thread 112 can havegenerally corresponding characteristics (e.g., lead, pitch, threads perinch, number of thread starts, pitch diameter, etc.). In one or moreaspects, the male and female threads 110, 112 include straight threads,in alternative aspects, the male and female threads 110, 112 aretapered. Accordingly, while the male and female threads 110, 112 mayhave corresponding characteristics, it is not necessary that threads110, 112 be uniform along their entire length. Indeed, male thread 110may have characteristics corresponding to those of female thread 112despite the characteristics changing along the respective lengths of pinend 104 or box end 108.

In one or more aspects, the male and female threads 110, 112 can includecharacteristics the same as or similar to those described in U.S. Pat.No. 5,788,401, the entire contents of which are incorporated byreference herein. For example, in one or more aspects, the male andfemale threads 110, 112 can comprise single start, helical taperedthreads. The male and female threads 110, 112 can have frusta-conicalcrests and roots with the taper being about 0.75 to 1.6 degrees. Themale and female threads 110, 112 can have a pitch of about 2.5 to 4.5threads/inc.

The male and female threads 110, 112 can also have negative pressureflank angles of about 7.5 to 15 degrees relative to a perpendicular todrill string central axis and clearance flanks of an angle of at least45 degrees to aid in maintaining the joint in a coupled condition, evenunder overload, and facilitate joint make up. Also, the box end and pinend can have shoulders tapered at about 5 to 10 degrees. Additionally,the pin crests can have an interference fit with the box roots while thebox crests are radially spaced from the pin roots to provide a rigidjoint while leaving a space for debris and pressurized lubricant. Onewill appreciate in light of the disclosure herein the foregoingdescription is just one configuration for the male and female threads110, 112. In alternative aspects, the configuration of the male andfemale threads 110, 112 can differ from the forgoing description.

As shown in FIGS. 1 and 2, the threads 110, 112 are illustrated ashaving a generally rectangular thread form. Such thread form is merelyone possible thread form that may be used. However, threads consistentwith the disclosure herein may have other thread forms. For instance, athread form may include a square, triangular, trapezoidal, or othershape.

In one or more aspects, the pin end 104 and/or the box end 108 mayinclude straight or tapered threads. For instance, the box end 108includes tapered threads 112. Inasmuch as the female threads 112 aretapered, the size of the thread 112 at or near the trailing edge 120 ofthe box end 108 may be larger than the size of male threads 110, and thefemale threads 112 may taper to a reduced size more similar to the sizeof male threads 110.

The male thread 110 can begin proximate a leading edge 114 of the pinend 104. For example, FIGS. 1 and 2 illustrate that the male thread 110can be offset a distance (shown has a linear distance 116) from theleading edge 114 of the pin end 104. The offset distance 116 may vary asdesired, and can particularly be different based on the size of thedrill string component 102, configuration of the thread 110, or based onother factors. In at least one aspect, the offset distance 116 isbetween about one-half and about twice the width 118 of the male thread110. Alternatively, the offset distance 116 may be greater or lesser.For example, in one or more aspects the offset distance 116 is zero suchthat the male thread 110 begins at the leading edge 114 of the pin end104.

Similarly, female thread 112 can begin proximate a trailing edge 120 ofthe box end 108. For example, FIGS. 1 and 2 illustrate that the femalethread 112 can be offset a distance (shown has a linear distance 122)from the trailing edge 120 of the box end 108. The offset distance 122may vary as desired, and can particularly be different based on the sizeof the drill string component 106, configuration of the female thread112, or based on other factors. In at least one aspect, the offsetdistance 122 is between about one-half and about twice the width 124 ofthe female thread 112. Alternatively, the offset distance 122 may begreater or lesser. For example, in one or more aspects the offsetdistance 122 is zero such that the female thread 112 begins at thetrailing edge 120 of the pin end 104.

Furthermore, the offset distance 116 can be equal to the offset distance122 as shown in FIG. 1. In alternative aspects, the offset distance 122may be greater or smaller than the offset distance 116. In any event, asthe leading edge 114 of the pin end 104 is inserted into the box end 108and rotated, the male thread 110 may engage the female thread 112, andthe pin end 104 may advance linearly along a central axis 126 of the boxend 108.

More particularly, the male and female threads 110, 112 can be helicallydisposed relative to the respective pin and box ends 104, 108. In otherwords, each of the male thread 110 and the female thread 112 cancomprise a plurality of helical turns extending along the respectivedrill string component 102, 106. As the male and female threads 110, 112mate, the threads may therefore rotate relative to each other and fitwithin gaps between corresponding threads. In FIGS. 1 and 2, the malethread 110 generally winds around pin end 104 at an angle 128, which canalso be measured relative to the leading edge 114 of the pin end 114.

In various aspects, the male thread 110 can include a thread width 118and the female thread 112 can include a thread width 124 as previouslymentioned. As used herein the term “thread width” can comprise thelinear distance between edges of a thread crest as measured along a linenormal to the edges of the thread crest. One will appreciate that thethread widths 118, 124 can vary depending upon the configuration of thethreads 110, 112. In one or more aspects, the thread width 118 of themale thread 110 is equal to the thread width 124 of the female thread112. In alternative aspects, the thread width 118 of the male thread 110is larger or smaller than the thread width 124 of the female thread 112.

In further aspects, the male thread 110 can include a thread depth 130and the female thread 112 can include a thread depth 132. As used hereinthe term “thread depth” can comprise the linear distance from thesurface from which the thread extends (i.e., the outer surface of thepin end 104 or inner surface of the box end 108) to most radially distalpoint on the thread crest as measured along a line normal to the surfacefrom which the thread extends. One will appreciate that the threaddepths 130, 132 can vary depending upon the configuration of the threads110, 112 and/or the size of the drill string components 102, 106. In oneor more aspects, the thread depth 130 of the male thread 110 is equal tothe thread depth 132 of the female thread 112. In alternative aspects,the thread depth 130 of the male thread 110 is larger or smaller thanthe thread depth 132 of the female thread 112.

In one or more aspects, the thread width 118, 124 of each thread 110,112 is greater than the thread depth 130, 132 of each thread 110, 112.For example, in one or more aspects, the thread width 118, 124 of eachthread 110, 112 is at least two times the thread depth 130, 132 of eachthread 110, 112. In alternative aspects, the thread width 118, 124 ofeach thread 110, 112 is approximately equal to or less than the threaddepth 130, 132 of each thread 110, 112.

As alluded to above, both the male and female threads 110, 112 caninclude a leading end or thread start. For example, FIGS. 1 and 2illustrate that the male thread 110 can include a thread start orleading end 134. Similarly, the female thread 112 can include a threadstart or leading end 136.

In one or more aspects, the leading end 134 of the male thread 110 cancomprise a planar surface that extends from the outer surface of the pinend 104. For example, the leading end 134 of the male thread 110 cancomprise a planar surface that extends radially outward from the outersurface of the pin end 104, thereby forming a face surface. In optionalaspects, the leading end 134 can extend in a direction normal to theouter surface of the pin end 104. In another aspect, the leading end 134can extend in a direction substantially normal to the outer surface ofthe pin end 104 (i.e., in a direction oriented at an angle less thanabout 15 degrees to a direction normal to the outer surface of the pinend 104). In still further aspects, the leading end 134 can comprise asurface that curves along at least a portion of one or more of itsheight or width.

Furthermore, in one or more aspects, the leading end 134 of the malethread 110 can extend the full thread width 118 of the male thread 110.In other words, the leading end 134 of the male thread 110 can extendfrom a leading edge 140 to a trailing edge 138 of the male thread 110.Thus, the planar surface forming the leading end 134 can span the entirethread width 118 of the male thread 110. It is optionally contemplatedthat the leading end 134 can span less than the entire thread width 118of the male thread 110.

Additionally, in one or more aspects the leading end 134 of the malethread 110 can extend the full thread depth 130 of the male thread 110.In other words, a height of the leading end 134 of the male thread 110can be equal to the thread depth 130. Thus, the planar surface formingthe leading end 134 can span the entire thread depth 130 of the malethread 110. As such, the leading end 134 or thread start can comprise anabrupt transition to the full depth and/or width of the male thread 110.In other words, in one or more aspects, the male thread 110 does notinclude a tail end that tapers gradually to the full depth of the malethread 110. However, it is optionally contemplated that the planarsurface forming the leading end 134 can span less than the entire threaddepth 130 of the male thread 110.

Along similar lines, the leading end 136 of the female thread 112 cancomprise a planar surface that extends from the inner surface of the boxend 108. For example, the leading end 136 of the female thread 112 cancomprise a planar surface that extends radially inward from the innersurface of the box end 108, thereby forming a face surface. In one ormore aspects the leading end 136 extends in a direction normal to theinner and/or outer surface of the box end 108. In alternative aspects,the leading end 136 extends in a direction substantially normal to theinner or outer surface of the box end 108 (i.e., in a direction orientedat an angle less than about 15 degrees to a direction normal to theinner and/or outer surface of the box end 108). In still furtheraspects, the leading end 136 can comprise a surface that curves alongone or more of its height or width. For example, the leading end 134 andthe leading end 136 can comprise cooperating curved surfaces.

Furthermore, in one or more aspects the leading end 136 of the femalethread 112 can extend the full thread width 124 of the female thread112. In other words, the leading end 136 of the female thread 112 canextend from a leading edge 142 to a trailing edge 144 of the femalethread 112. Thus, the planar surface forming the leading end 136 canspan the entire thread width 124 of the female thread 112.

Additionally, in one or more aspects the leading end 136 of the femalethread 112 can extend the full thread depth 132 of the female thread112. In other words, a height of the leading end 136 of the femalethread 112 can be equal to the thread depth 132. Thus, the planarsurface forming the leading end 136 can span the entire thread depth 132of the female thread 112. As such, the leading end 136 or thread startcan comprise an abrupt transition to the full depth and/or width of thefemale thread 112. In other words, in one or more aspects, the femalethread 112 does not include a tail end that tapers gradually to the fulldepth of the female thread 112. In the illustrated aspect, the leadingend or thread start 136 of the female thread 112 is illustrated as beingformed by material that remains after machining or another process usedto form the threads. Thus, the leading end or thread start 136 may be,relative to the interior surface of the box end 108, embossed ratherthan recessed.

In one or more aspects, the leading end 134 of the male thread 110 canhave a size and/or shape equal to the leading end 136 of the femalethread 112. In alternative aspects, the size and/or shape of the leadingend 134 of the male thread 110 can differ from the size and/or shape ofthe leading end 136 of the female thread 112. For example, in one ormore aspects, the leading end 134 of the male thread 110 can be largerthan the leading end 136 of the female thread 112.

In one or more aspects, the leading ends 134, 136 of the male and femalethreads 110, 112 can each have an off-axis orientation. In other words,the planar surfaces of the leading ends 134, 136 of the male and femalethreads 110, 112 can each extend in a direction offset or non-parallelto a central axis 126 of the drill string components 102, 106. Forexample, as illustrated by FIG. 1, the planar surface of the leading end134 of the male thread 110 can face an adjacent turn of the male thread110. Similarly, the planar surface of the leading end 136 of the femalethread 112 can face an adjacent turn of the female thread 112.Optionally, as illustrated by FIG. 2, the planar surface of the leadingend 134 of the male thread 110 can face toward the leading edge 114 ofthe pin end 104. Similarly, the planar surface of the leading end 136 ofthe female thread 112 can face toward the trailing edge 120 of the boxend 108. In further aspects, it is contemplated that the planar surfaceof the leading end 134 of the male thread 110 can face toward theleading edge 114 of the pin end 104 and the planar surface of theleading end 136 of the female thread 112 can face an adjacent turn ofthe female thread 112. Similarly, in yet another aspect, it iscontemplated that the planar surface of the leading end 134 of the malethread 110 can face an adjacent turn of the male thread 110 and theplanar surface of the leading end 136 of the female thread 112 can facetoward the trailing edge 120 of the box end 108.

More particularly, the planar surface of the leading end 134 of the malethread 110 can extend at an angle relative to the leading edge 114 orthe central axis 126 of the pin end 104. For instance, in FIGS. 1 and 2,the planar surface of the leading end 134 of the male thread 110 can beoriented at an angle 146 relative to the central axis 126 of the drillstring component 102, although the angle may also be measured relativeto the leading edge 114. The illustrated orientation and existence of aplanar surface of the leading end 134 is particularly noticeable whencompared to traditional threads, which taper to a point such that thereis virtually no distance between the leading and trailing edges of athread, thereby providing no face surface.

Similar to the leading end 134, the leading end 136 of the female thread112 can extend at an angle relative to the trailing edge 120 or thecentral axis 126 of the pin end 104. For instance, in FIG. 1, the planarsurface of the leading end 136 of the female thread 112 is oriented atan angle 148 relative to the central axis 126 of the drill stringcomponent 106, although the angle may also be measured relative to thetrailing edge 120.

The angles 146, 148 can be varied in accordance with the presentdisclosure and include any number of different angles. The angles 146,148 may be varied based on other characteristics of the threads 110,112, or based on a value that is independent of thread characteristics.In one or more aspects, angle 146 is equal to angle 148. In alternativeaspects, the angle 146 can differ from angle 148.

In one or more aspects the angles 146, 148 are each acute angles. Forexample, each of the angles 146, 148 can comprise an angle between about10 degrees and 80 degrees, about 15 degrees and about 75 degrees, about20 degrees and about 70 degrees, about 30 degrees and about 60 degrees,about 40 degrees and about 50 degrees. In further aspects, the angles146, 148 can comprise about 45 degrees. One will appreciate in light ofthe disclosure herein that upon impact between two mating leading ends134, 136 or start faces with increasing angles 146, 148, there isdecreasing loss of momentum and decreasing frictional resistance todrawing the threads 110, 112 into a fully mating condition. In anyevent, a leading end 134 of the male thread 110 can mate with theleading end 136 of the female thread 112 to aid in making a jointbetween the first drill string component 102 and the second drill stringcomponent 106.

By eliminating the long tail of a thread start and replacing the tailwith a more abrupt transition to the full height of the thread 110, 112,a leading ends 134, 136 or thread start face can thus be provided.Moreover, while the leading ends 134, 136 may be angled or otherwiseoriented with respect to an axis 126, the thread start face may also benormal to the major and/or minor diameters of cylindrical surfaces ofthe corresponding pin and box ends 104, 108. Such geometry eliminates atail-type thread start that can act as a wedge, thereby eliminatinggeometry that leads to wedging upon mating of the pin and box ends 104,108.

Moreover, as the pin and box ends 104, 108 are drawn together, theleading ends 134, 136 or thread starts may have corresponding surfacesthat, when mated together, create a sliding interface in a nearthread-coupled condition. For instance, where the leading ends 134, 136are each oriented at acute angles, the leading ends 134, 136 or threadstart faces may engage each other and cooperatively draw threads into afully thread-coupled condition. By way of example during make up of adrill rod assembly, as the pin end 104 is fed into the box end 108, theleading ends 134, 136 can engage and direct each other intocorresponding recesses between threads. Such may occur during rotationand feed of one or both of the drill string components 102, 106.Furthermore, since thread start tails are eliminated, there are few—ifany—limits on rotational positions for mating. Thus, the pin and boxends 104, 108 can have the full circumference available for mating, withno jamming prone positions.

In one or more aspects, a thread 110 may be formed with a tail usingconventional machining processes. The tail may be least partiallyremoved to form the leading end 134. In such aspects, a tail may extendaround approximately half the circumference of a given pin end 104.Consequently, if the entire tail of the thread 110 is removed, thethread 110 may have a leading end 134 aligned with the axis 126. If,however, more of the thread 110 beyond just the tail is removed, leadingend 134 may be offset relative to the axis 126. The tail may be removedby a separate machining process.

Although this example illustrates the removal of a tail for formation ofa thread start, in other embodiments a thread start face may be formedin the absence of creation and/or subsequent removal of a tail-typethread start. For example, instead of using conventional machiningprocesses, the thread is formed using electrical discharge machiningElectrical discharge machining can allow for the formation of theleading end 134 since metal can be consumed during the process.Alternatively, electrochemical machining or other processes that consumematerial may also be used to form the leading ends 134, 136 of thethreads 110, 112.

As previously mentioned, in one or more aspects the drill stringcomponents 102, 106 can comprise hollow bodies. More specifically, inone or more aspects the drill string components can be thin-walled. Inparticular, as shown by FIG. 1, the drill string component 106 caninclude an outer diameter 150, an inner diameter 152, and a wallthickness 154. The wall thickness 154 can equal one half of the outerdiameter 150 minus the inner diameter 152. In one or more aspects, thedrill string component 106 has a wall thickness 154 between aboutapproximately 5 percent and 15 percent of the outer diameter 150. Infurther aspects, the drill string component 106 has a wall thickness 154between about approximately 6 percent and 8 percent of the outerdiameter 150. One will appreciate that such thin-walled drill stringcomponents can limit the geometry of the threads 112. However, athin-walled drill string component can nonetheless includes a leadingend 134, 136 as described hereinabove despite such limitations.

Referring now to FIG. 3, the drill string components 102, 106 cancomprise any number of different types of tools. In other words,virtually any threaded member used on a drill string can include one ormore of a box end 108 and a pin end 104 having leading ends or threadstarts as described in relation to FIGS. 1 and 2. For example, FIG. 3illustrates that drill string components can include a locking coupling201, an adaptor coupling 202, a drill rod 204, and a reamer 206 can eachinclude both a pin end 104 and a box end 108 with leading ends 134, 136that resist or reduce jamming and cross-threading as described above inrelation to FIG. 1. FIG. 3 further illustrates that drill stringcomponents can include a stabilizer 203, a landing ring 205 and a drillbit 207 including a box end 108 with a leading end 136 that resists orreduces jamming and cross-threading as described above in relation toFIG. 1. In yet further aspects, the drill string components 102, 106 cancomprise casings, reamers, core lifters, or other drill stringcomponents.

Referring now to FIG. 4, a drilling system 300 may be used to drill intoa formation 304. The drilling system 300 may include a drill string 302formed from a plurality of drill rods 204 or other drill stringcomponents 201-207. The drill rods 204 may be rigid and/or metallic, oralternatively may be constructed from other suitable materials. Thedrill string 302 may include a series of connected drill rods that maybe assembled section-by-section as the drill string 302 advances intothe formation 304. A drill bit 207 (for example, an open-faced drill bitor other type of drill bit) may be secured to the distal end of thedrill string 302. As used herein the terms “down,” “lower,” “leading,”and “distal end” refer to the end of the drill string 302 including thedrill bit 207. While the terms “up,” “upper,” “trailing,” or “proximal”refer to the end of the drill string 302 opposite the drill bit 207.

The drilling system 300 may include a drill rig 301 that may rotateand/or push the drill bit 207, the drill rods 204 and/or other portionsof the drill string 302 into the formation 304. The drill rig 301 mayinclude a driving mechanism, for example, a rotary drill head 306, asled assembly 308, and a mast 310. The drill head 306 may be coupled tothe drill string 302, and can rotate the drill bit 207, the drill rods204 and/or other portions of the drill string 302. If desired, therotary drill head 306 may be configured to vary the speed and/ordirection that it rotates these components. The sled assembly 308 canmove relative to the mast 310. As the sled assembly 308 moves relativeto the mast 310, the sled assembly 308 may provide a force against therotary drill head 306, which may push the drill bit 207, the drill rods204 and/or other portions of the drill string 302 further into theformation 304, for example, while they are being rotated.

It will be appreciated, however, that the drill rig 301 does not requirea rotary drill head, a sled assembly, a slide frame or a drive assemblyand that the drill rig 301 may include other suitable components. Itwill also be appreciated that the drilling system 300 does not require adrill rig and that the drilling system 300 may include other suitablecomponents that may rotate and/or push the drill bit 207, the drill rods204 and/or other portions of the drill string 302 into the formation304. For example, sonic, percussive, or down hole motors may be used.

As shown by FIG. 4, the drilling system 300 can further include a drillrod drill rod clamping device 312. In further detail, the drivingmechanism may advance the drill string 302 and particularly a firstdrill rod 204 until a trailing portion of the first drill rod 204 isproximate an opening of a borehole formed by the drill string 302. Oncethe first drill rod 204 is at a desired depth, the drill rod clampingdevice 312 may grasp the first drill rod 204, which may help preventinadvertent loss of the first drill rod 204 and the drill string 302down the borehole. With the drill rod clamping device 312 grasping thefirst drill rod 204, the driving mechanism may be disconnected from thefirst drill rod 204.

An additional or second drill rod 204 may then be connected to thedriving mechanism manually or automatically using a drill rod handlingdevice, such as that described in U.S. Patent Application PublicationNo. 2010/0021271, the entire contents of which are hereby incorporatedby reference herein. Next driving mechanism can automatically advancedthe pin end 104 of the second drill rod 204 into the box end 108 of thefirst drill rod 204. A joint between the first drill rod 204 and thesecond drill rod 204 may be made by threading the second drill rod 204into the first drill rod 204. One will appreciate in light of thedisclosure herein that the leading ends 134, 136 of the male and femalethreads 110, 112 of the drill rods 204 can prevent or reduce jamming andcross-threading even when the joint between the drill rods 204 is madeautomatically by the drill rig 301.

After the second drill rod 204 is connected to the driving mechanism andthe first drill rod 204, the drill rod clamping device 312 may releasethe drill 302. The driving mechanism may advance the drill string 302further into the formation to a greater desired depth. This process ofgrasping the drill string 302, disconnecting the driving mechanism,connecting an additional drill rod 204, releasing the grasp, andadvancing the drill string 302 to a greater depth may be repeatedlyperformed to drill deeper and deeper into the formation.

Accordingly, FIGS. 1-4, the corresponding text, provide a number ofdifferent components and mechanisms for making joints between drillstring components while reducing or eliminating jamming andcross-threading. In addition to the foregoing, aspects of the presentinvention can also be described in terms acts and steps in a method foraccomplishing a particular result. For example, a method of a method ofmaking a joint in a drill string without jamming or cross threading isdescribed below with reference to the components and diagrams of FIGS. 1through 4.

The method can involve inserting a pin end 104 of a first drill stringcomponent 102 into a box end 108 of a second drill string component 106.The method can also involve rotating the first drill sting component 102relative to the second drill string component 108. The method canfurther involve abutting a planar leading end 134 of a male thread 110on the pin end 104 of the first drill string component 102 against aplanar leading end 136 of a female thread 112 on the box end 108 of thesecond drill string component 106.

The planar leading end 134 of the male thread 110 can be oriented at anacute angle 146 relative to a central axis 26 of the first drill stringcomponent 102. Similarly, the planar leading end 136 of the femalethread 112 can be oriented at an acute angle 148 relative to a centralaxis 26 of the second drill string component 106.

The method can further involve sliding the planar leading end 134 of themale thread 110 against and along the planar leading end 136 of thefemale thread 112 to guide the male thread 110 into a gap between turnsof the female thread 112. Sliding the planar leading end 134 of the malethread 110 against and along the planar leading end 136 of the femalethread 112 can cause the first drill string component 102 to rotaterelative to the second drill string component 106 due to the acuteangles 146, 148 of the planar leading ends 134, 136 of the male andfemale threads 110, 112. The method can involve automatically rotatingand advancing the first drill sting component 102 relative to the seconddrill string component 106 using a drill rig 301 without manuallyhandling the drill string components 106, 108.

The planar leading end 136 of the female thread 112 can extend along anentire depth 132 of the female thread 110. The planar leading end 134 ofthe male thread 110 can extend along an entire depth 130 of the malethread 110. When rotating the first drill sting component 102 relativeto the second drill string component 108, the depths of the planarleading ends 134, 136 of the female thread 112 and the male thread 110can prevent jamming or wedging of the male and female threads 110, 112.

Thus, aspects of the foregoing provide various desirable features. Forinstance, by including leading ends or start faces which are optionallythe full width of the thread, the tail-type thread start can beeliminated, thereby allowing: (a) substantially full circumferencerotational positioning for threading; and (b) a guiding surface forplacing mating threads into a threading position. For instance, theangled start face can engage a corresponding thread or thread start faceand direct the corresponding thread into a threading position betweenhelical threads. Moreover, at any position of the corresponding threads,the tail has been eliminated to virtually eliminate wedging pronegeometry.

Similar benefits may be obtained regardless of whether threading isconcentric or off-center in nature. For instance, in an off-centerarrangement, a line intersecting a thread crest and a thread start facemay include a joint taper. Under feed, the thread start face can matewith the mating thread crest in a manner that reduces or eliminateswedging as the intersection and subsequent thread resist wedging,jamming, and cross-threading. In such an embodiment, a joint taper maybe sufficient to reduce the major diameter at a smaller end of a malethread to be less than a minor diameter at a large end of a femalethread. Thus, off-center threading may be used for tapered threads.

Threads of the present disclosure may be formed in any number ofsuitable manners. For instance, as described previously, turning devicessuch as lathes may have difficultly creating an abrupt thread start facesuch as those disclosed herein. Accordingly, in some embodiments, athread may be formed to include a tail. A subsequent grinding, milling,or other process may then be employed to remove a portion of the tailand create a thread start such as those described herein, or may belearned from a review of the disclosure herein. In other embodiments,other equipment may be utilized, including a combination of turning andother machining equipment. For instance, a lathe may produce a portionof the thread while other machinery can further process a male or femalecomponent to add a thread start face. In still other embodiments,molding, casting, single point cutting, taps and dies, die heads,milling, grinding, rolling, lapping, or other processes, or anycombination of the foregoing, may be used to create a thread inaccordance with the disclosure herein.

The present invention can thus be embodied in other specific formswithout departing from its spirit or essential characteristics. Thedescribed embodiments are to be considered in all respects only asillustrative and not restrictive. The scope of the invention is,therefore, indicated by the appended claims rather than by the foregoingdescription. All changes that come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

What is claimed is:
 1. A threaded drill string component that resistsjamming and cross threading, comprising: a hollow body having a firstend, an opposing second end, and a central axis extending through thehollow body; and a thread positioned on the first end of the hollowbody; wherein: the thread comprises a plurality of helical turnsextending along the first end of the hollow body, the thread has athread depth and a thread width, the thread comprises a leading endproximate the first end of the hollow body, the leading end of thethread is orientated at an acute angle relative to the central axis ofthe hollow body, and the leading end of the thread faces toward thefirst end of the hollow body.
 2. The drill string component as recitedin claim 1, wherein the leading end of the thread comprises a planarsurface extending normal to the hollow body.
 3. The drill stringcomponent as recited in claim 2, wherein the planar surface of theleading end of the thread extends the full thread width.
 4. The drillstring component as recited in claim 1, wherein the leading end of thethread has a height equal to the thread depth.
 5. The drill stringcomponent as recited in claim 4, wherein the thread width is greaterthan the thread depth.
 6. The drill string component as recited in claim5, wherein thread width is at least two times the thread depth.
 7. Thedrill string component as recited in claim 1, wherein the acute angle isbetween approximately 15 degrees and approximately 75 degrees.
 8. Thedrill string component as recited in claim 7, wherein the acute angle isbetween approximately 30 degrees and approximately 60 degrees.
 9. Thedrill string component as recited in claim 8, wherein the acute angle isbetween approximately 40 degrees and approximately 50 degrees.
 10. Thedrill string component as recited in claim 1, wherein the hollow body isa thin-walled body having a wall thickness between approximately 5percent and 15 percent of an outer diameter of the hollow body.
 11. Thedrill string component as recited in claim 1, wherein the first endcomprises a box end and the thread comprises a female thread.
 12. Thedrill string component as recited in claim 11, further comprising asecond thread positioned on the second end of the hollow body; wherein:the second thread comprises a plurality of helical turns extending alongthe second end of the hollow body, the second thread comprises a leadingend proximate the second end of the hollow body, the leading end of thesecond thread is orientated at an acute angle relative to the centralaxis of the hollow body, and the leading end of the second thread facestoward the leading end of the hollow body.
 13. The drill stringcomponent as recited in claim 12, wherein the second end comprises a pinend and the second thread comprises a male thread.
 14. The drill stringcomponent as recited in claim 1, wherein the drill string componentcomprises one of a drill rod, a casing, an adaptor coupling, a reamer, adrill bit, a core lifter, a locking coupling, a landing ring, or astabilizer.
 15. The drill string component as recited in claim 1,wherein the leading end of the thread is offset from the first end ofthe hollow body by a distance equal to or less than about the threadwidth.
 16. A threaded drill string component that resists jamming andcross threading, comprising: a body, a box end, an opposing pin end, anda central axis extending through the body; a female thread positioned onthe box end of the body, the female thread having a depth and a width; amale thread positioned on the pin end of the body, the male threadhaving a depth and a width; wherein: each of the female thread and themale thread comprises a leading end, the leading end of each of thefemale thread and the male thread comprises a planar surface extendingnormal to the body, the planar surface of the leading end of the femalethread extends along the entire width and the entire depth of the femalethread, and the planar surface of the leading end of the male threadextends along the entire width and the entire depth of the male thread.17. The drill string component as recited in claim 16, wherein: each ofthe female thread and the male thread comprises a plurality of helicalturns; the leading end of the female thread faces toward the box end ofthe body; and the leading end of the male thread faces toward the pinend of the body.
 18. The drill string component as recited in claim 17,wherein the planar surfaces of the female thread and the male threadeach extend at an acute angle relative to the central axis of the body.19. The drill string component as recited in claim 18, wherein the acuteangle is between approximately 15 degrees and approximately 75 degrees.20. The drill string component as recited in claim 19, wherein the drillstring component comprises a drill rod.
 21. The drill string componentas recited in claim 20, wherein the drill rod is hollow and thin-walled.22. A method of making a joint in a drill string without jamming orcross threading, comprising: inserting a pin end of a first drill stringcomponent into a box end of a second drill string component; rotatingthe first drill sting component relative to the second drill stringcomponent and thereby abutting a planar leading end of a male thread onthe pin end of the first drill string component against a planar leadingend of a female thread on the box end of the second drill stringcomponent; wherein the planar leading end of the male thread is orientedat an acute angle relative to a central axis of the first drill stringcomponent; wherein the planar leading end of the female thread isoriented at an acute angle relative to a central axis of the seconddrill string component; and sliding the planar leading end of the malethread against and along the planar leading end of the female threadguides the male thread into a gap between turns of the female thread.23. The method of making a joint in a drill string as recited in claim22, wherein sliding the planar leading end of the male thread againstand along the planar leading end of the female thread causes the firstdrill string component to rotate relative to the second drill stringcomponent due to the acute angle of the planar leading ends of the maleand female threads.
 24. The method of making a joint in a drill stringas recited in claim 22, further comprising automatically rotating andadvancing the first drill sting component relative to the second drillstring component.
 25. The method of making a joint in a drill string asrecited in claim 22, wherein: the planar leading end of the femalethread extends along an entire depth of the female thread; the planarleading end of the male thread extends along an entire depth of the malethread; when rotating the first drill sting component relative to thesecond drill string component the depths of the planar leading ends ofthe female thread and the male thread prevent jamming or wedging of themale and female threads.